Which term describes pain radiating from the back to the hip and down the leg?

The term that describes pain radiating from the back to the hip and down the leg is "Sciatica." This condition occurs when the sciatic nerve, which runs from the lower back, through the hips, and down each leg, becomes compressed or irritated. Sciatica pain typically starts in the lower back or buttock and radiates along the pathway of the nerve, commonly affecting one side of the body. This radiating pain is often accompanied by symptoms such as numbness, weakness, or tingling in the leg.

In contrast, epilepsy refers to a neurological disorder characterized by recurrent seizures. Meningitis is an inflammation of the protective membranes covering the brain and spinal cord, often due to infection, and can cause severe headaches and other systemic symptoms but does not typically cause radiating leg pain. A herniated disk can lead to sciatica if it presses on the sciatic nerve but is specifically an anatomical issue rather than a description of the symptom itself. Hence, sciatica captures the essence of the symptom described in the question.